The present invention relates to the field of loading ramps and, more specifically, to loading ramps and the like which may be rolled up for convenient storage and transport.
Loading ramps of many types have been known and are commonly used to unload pick-up trucks, delivery trucks and the like. Further, these ramps may be used to allow wheeled vehicles to traverse short sets of steps. As these ramps are often used with mobile vehicles, it is desirable that the ramps be highly portable and storable. As such, several varieties of folding ramps are known. Typically, these ramps may fold in a rectangular or square fashion and pile on top of each other. As these ramps may be used to unload very heavy loads, considerable strength may be necessary when designing and using these ramps. The strength necessary along with the desirability of making a ramp easily portable has created a problem in that ramps which are easily portable may often be light and lack the requisite strength needed, whereas ramps of a sufficient amount of strength to move heavier loads may be large and bulky.
It is therefore an object of the present invention to provide a ramp which may be rolled for easy and convenient storage which is both light and easy to use while still having the requisite strength needed for a given job. Further, it is desirable that this ramp be easy to use and contain other features lending to the utility of the present invention.
It is the primary objective of the present invention to provide a method by which wheeled vehicles, such as wheelchairs and utility vehicles (including garden tractors and recreational vehicles), can be easily loaded into the back load carrying portion of larger vehicles such as pickup trucks and cargo or minivans.
It is an additional objective of the present invention to provide such a loading device that can be rolled up for easy and compact storage when the device is not in use and which is constructed in a manner and of a material that makes it light weight enough for almost all individuals of a large variety of physical capabilities.
It is a further objective of the present invention to provide such a loading device that, when in its unrolled and deployed orientation, is strong enough to easily support the weight of the vehicles and their occupants that are typically loaded and transported in this manner.
It is a still further objective of the present invention to provide such a loading device that is relatively simple and inexpensive in its design and construction which allows it to be used by average people without the need for specialized tools or knowledge.
These objectives are accomplished by the use of a series of interlocking rectangular metallic or non-metallic links that are pivotally attached to one another at both of their longer sides. By attaching enough of these links together in this fashion, a bridge-like structure is created that can be used to span the gap between the surface upon which a supplemental vehicle rests and the load bed of a transporting vehicle such as a pickup truck or van. This loading process is accomplished by placing one or more of these structures, depending upon the number and orientation of the wheels on the supplemental vehicle, between the vehicle bed and ground or surface upon which the supplemental vehicle rests, and then driving or pushing the supplemental vehicle up the ramp and into the transport vehicle. The unloading of the supplemental vehicle is accomplished simply by reversing this process.
Once the loading or unloading is accomplished, the design of the present invention allows it to be rolled up into a compact cylindrical form that can be easily stored in a relatively small area or volume. The individual links of the present invention are specifically designed in a manner that allows for this rolling and unrolling process and also allows the ramp to be extended out and employed to span relatively large distances and support a great deal of weight without the use of additional support structures. These attributes of the invention are accomplished by the manner of construction of the surfaces of the individual links where they are joined to one another and by the method used to make the connections of the links.
Each individual link has on its forward and rearward facing surfaces extending tab-like features which are hemispherically shaped and each laterally offset in a manner that allows them to be mated to corresponding tabs on other links. Each of the tabs also contain a cylindrical hole that passes laterally through it just behind the hemispherically shaped leading edge and which correspond in location to other such holes when the tabs are mated during the link joining process. Therefore, when a plurality of links are placed end to end, the offset tabs of one slide next to the tabs of its neighbor to the point where their centrally located holes align. The connection of the two links is completed by passing a pressure fitted pin through this hole which defines a pivotal axis between the links. This design allows each of the individual links to pivot in relation to one another around this axis. This pivoting motion is the aspect of the present invention which allows it to be rolled up for storage purposes.
The individual links of the invention are also designed to halt the pivoting motion at the proper point as to form the bridge-like span which is central to its purpose. This is accomplished by the design of the vertically oriented link contact surfaces of the links that make up the span. These link contact surfaces are formed so that they are oriented at nearly right angles (they are actually slightly inwardly oriented in relation to the body of the link) to the other surfaces of the link. The major importance of the design of the link contact surfaces is the manner in which they interact with the link contact surfaces of their neighboring links in the span of the invention. It is this interaction of two link contact surfaces which provides load bearing functions of the invention as the slight angle of their construction imparts a slight upward bow or cumber to the span of the invention when it is fully deployed which adds strength to the span. Additionally, the relationship between the location of the pivot point (at the lower surface of the links) and these link contact surfaces (at the upper surface of the links) focuses the load carried by the invention on to the link contact surfaces.
The individual links are also designed with an upper surface which has both raised ridges for improved traction and plurality of areas where material has been removed for weight reduction purposes. These features provide a ramp that is safe for people of all abilities to operate and one that can be easily handled and transported because of its overall light weight while maintaining the structural rigidity necessary to carry the loads it was designed for.
An optional hinging mechanism is also provided that allows the present invention to be stored in a folded orientation rather than the rolled manner as described above. The need for this optional hinging mechanism is that the design of the primary pivot tabs limits their inward travel. That is to say, when pivoting the individual links towards each other, the direct liking of the pivot tabs prohibits the neighboring links from completely folding to a parallel orientation with respect to one another. While this design allows the invention to be completely and easily rolled for storage, it does not allow it to be folded into two shorter and parallel spans for transport and storage purposes.
To facilitate this folding function, an alternative pivoting link may be obtained which allows the user to create a 180xc2x0 fold in the ramp span. The 180xc2x0 hinge allows for this folding function by moving the pivot point between two neighboring links from the single pivot point between the pivot tabs located at the lowest and outside points of each link, to two pivot points located on the center line of each link in a position removed from the outside edge of the links which are then spanned by a pivoting bracket. The use of the double pivot points to join two neighboring links allows those links to be folded in a completely parallel manner which in turn allows the span of the present invention to be folded into two equal halves. This allows the invention to be stored in this folded manner when space is not such a significant issue. Additionally, this method of storage allows the invention to be deployed and stored more quickly which enhances its overall utility.
Additionally, the present invention can also be fitted with a powered winch-like device which can be employed by a user to pull a wheelchair (or other wheeled vehicle) and its occupant up the incline of the ramp span. This optional device is useful for those individuals who do not have a powered wheelchair and who are physically impaired to a degree that makes it difficult for them to manually drive the wheelchair up the incline of the invention. Therefore, the use of the powered chair lift assembly provides such individuals with a greater degree of independence as it allows them to gain access to areas that they would otherwise need the assistance of others to enter.
The powered chair lift assembly uses an electric motor to drive a large and small pulley which each have the ends of a braided steel cable attached to them. This cable forms a loop which extends forward around an idler pulley positioned at the end of a bar extension. The idler pulley allows the cable to be directed back over the body of the powered chair lift assembly and down the ramp span to a position where it can be connected to a wheelchair. Once this connection has been established, the user then remotely engages the electric motor which rotates the pulleys which acts to shorten the cable. This shortening of the cable draws the attached wheelchair towards the powered chair lift assembly, thus, pulling the wheelchair and its occupant up the incline of the ramp span.
An additional optional feature is available for use with the present invention which consists of an elevated hand rail that can be fitted to the existing components of the ramp span. The hand rail is made of a relatively broad rail that is positioned at an appropriate height by the use of a plurality of hand rail posts. The hand rail posts are constructed in such a manner so that their lower ends fit over the link rails of the link body in a fashion that allows them to be easily bolted into a upright and ridged position. The upper portion of the hand rail posts are similarly constructed so that they conform to the shape of the lower surface of the hand rail which enables it to be easily attached at this end as well. The use of the hand rail provides an extra degree of safety to those individuals who are able to walk but require the additional stability of a hand support while ascending or descending an inclined surface.
A still further optional feature is available for use with the present invention which uses a double end plate arrangement to increase the load carrying capacity of a deployed ramp span. In this configuration a double end plate is attached to each outer surface of the ramp links. The double end plates are constructed in exactly the same configuration as the outer surfaces of the ramp links and also connect in sequence in the same fashion as the ramp links. The connection between the double end plates and the ramp links is made by removing the pivot bolt holding the joined ramp links together, placing a double ramp link in such a location so that it matches the orientation of the underlying outer surface of the ramp link, and replacing the pivot bolt with a long pivot bolt which passes through the link pivot tabs of both the double ramp link and the underlying ramp link.
Additionally, since the weakest point of a deployed ramp span is located at its center portion, it will only be necessary to add the double end plates to those ramp links located at or near its center to increase its load capacity by as much as a factor of 2. This configuration enhances the usefulness of the ramp span as it greatly increases its carrying capacity without affecting its roll-up capabilities or significantly increasing its overall weight.